When I search wikipedia by typing 'w query' in the location bar opera shows me a page in the language of the country that I am currently in.
Is there a way to change this to a fixed language? The VPN does not affect the language.
You can check the language option from the Windows FAQ but will change other searches also, don't know if that will make troubles to you.
To unhide system files, you can use this.
Another option could be to create a new Wiki search with the desired country/language.
Use the search engine preferences. opera://settings/searchEngines
I don't see a way to edit the built-in default search engines, but you could simply create a new one with the keyword 'wfr' say for French, and use the url https://fr.wikipedia.org/w/index.php?search=%s